Director Paula Dowdy adds 109,890 Quantum-Si (QSI) shares in open-market buy

Rhea-AI Filing Summary

Quantum-Si Inc director Paula Dowdy purchased Class A common stock in an open-market transaction. On March 5, 2026, she bought 109,890 shares at a weighted average price of $0.9505 per share, and held 269,107 shares directly after the trade.

The footnote explains that the $0.9505 figure is a weighted average, with actual purchase prices ranging from $0.9051 to $0.9730 per share. Detailed price breakdowns are available upon request from regulators, the company, or its security holders.

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Dowdy Paula

(Last) (First) (Middle)

C/O QUANTUM-SI INCORPORATED

29 BUSINESS PARK DRIVE

(Street)

BRANFORD CT 06405

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Quantum-Si Inc [ QSI ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
03/05/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Class A Common Stock	03/05/2026		P		109,890	A	$0.9505(1)	269,107	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. Represents the weighted average purchase price per share. The shares were purchased at prices ranging from $0.9051 to $0.9730 per share. Full information regarding the number of shares purchased at each price shall be provided upon request to the staff of the U.S. Securities and Exchange Commission, the Issuer, or a security holder of the Issuer.

	/s/ Christian LaPointe, Ph.D., Attorney-in-Fact.	03/09/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

FAQ

What insider transaction did Quantum-Si (QSI) director Paula Dowdy report?

Quantum-Si (QSI) director Paula Dowdy reported an open-market purchase of Class A common stock. She bought 109,890 shares on March 5, 2026, increasing her direct holdings to 269,107 shares following the transaction at a weighted average price of $0.9505 per share.

How many Quantum-Si (QSI) shares did Paula Dowdy buy and at what price?

Paula Dowdy bought 109,890 Quantum-Si (QSI) Class A shares in an open-market purchase. The weighted average price was $0.9505 per share, with individual purchase prices ranging from $0.9051 to $0.9730 according to the reported price range in the filing footnote.

What is Paula Dowdy’s Quantum-Si (QSI) share ownership after this Form 4 trade?

After the reported transaction, Paula Dowdy directly owns 269,107 Quantum-Si (QSI) Class A common shares. This total reflects her holdings immediately following the March 5, 2026 open-market purchase of 109,890 additional shares reported in the Form 4 filing.

Was the Quantum-Si (QSI) insider transaction a buy or a sell?

The Quantum-Si (QSI) insider transaction was a buy. Director Paula Dowdy executed an open-market purchase of 109,890 Class A common shares on March 5, 2026, as indicated by transaction code “P” and the buy classification in the Form 4 data.

What price range did Quantum-Si (QSI) shares trade at in Paula Dowdy’s purchase?

The filing states that Paula Dowdy’s Quantum-Si (QSI) share purchases occurred between $0.9051 and $0.9730 per share. The reported transaction price of $0.9505 is a weighted average across these trades, with detailed price breakdowns available upon request to authorized parties.

How is the weighted average price calculated in Paula Dowdy’s Quantum-Si (QSI) trade?

The weighted average price of $0.9505 for Paula Dowdy’s Quantum-Si (QSI) trade reflects multiple purchases at different prices. Shares were bought between $0.9051 and $0.9730, and the average is based on the number of shares purchased at each individual price in that range.